In this Sept. 15, 2017, photo, President Donald Trump speaks to military personnel and their families at Andrews Air Force Base, Md. At this week's U.N. General Assembly, Trump will find there are serEvan Vucci/AP

Iranian President Hassan Rohani told CNN on Monday that the U.S. would pay a hefty price for scrapping its nuclear deal with Tehran, a measure U.S. President Donald Trump has vowed to take if Washington deems that the UN agency monitoring the accord is not stringent enough in doing so.

“Exiting such an agreement would carry a high cost for the United States of America, and I do not believe Americans would be willing to pay such a high cost for something that will be useless for them,” Rohani said.

Hours before his meeting with Prime Minister Benjamin Netanyahu, Trump said that the U.S. “will not accept a weakly enforced or inadequately monitored deal” in a message read by U.S. Energy Secretary Rick Perry at a meeting of the International Atomic Energy Agency.

According to Rohani, however, pulling out of the accord “will yield no results for the United States but at the same time it will generally decrease and cut away and chip away at international trust placed in the Unites States of America.”

"It is essential to maintain it to avoid proliferation. In this period when we see the risks with North Korea, we must maintain this line," Le Drian told reporters on the sidelines of the UN General Assembly's annual gathering in New York. He also suggested that there could be talks to strengthen the pact for the post-2025 period.

"France will try to convince President Trump of the pertinence of this choice (keeping the accord) even if work can be done to complement the accord (after 2025)," Le Drian said.

Tehran has said that the greatest threat to the deal is "the American administration's overly hostile attitude.” Alluding to U.S. assertions that the deal allows the IAEA to inspect Tehran's military sites, Iranian nuclear chief Ali Akbar Salehi is urging the agency to "resist such unacceptable demands."

In 2016, a few months after the nuclear agreement with Iran went into effect, a Western entity gave the International Atomic Energy Agency information regarding sites the Islamic republic did not report as part of its nuclear program and where, according to suspicions, forbidden nuclear military research and development activity was being conducted, Israeli officials involved in the issue told Haaretz's Barak Ravid on Saturday.

The Western entity also shared the information with a number of the six world powers who were party to the nuclear agreement, officials said.

The officials noted that almost all the suspected sites have not been visited by IAEA inspectors – either because of Iran’s refusal to grant entry or UN officials’ reluctance to confront Iran on the issue.

According to the Israeli officials, even when the Iranians granted inspectors access to the suspected sites, it only did so after a substantial amount of time had passed and created significant obstacles.

“At one point we saw there was no one to talk to,” said one of the Israeli officials. “There is a whole list of suspicious sites where the Iranians do not allow inspectors to visit and no one enforces the supervision mechanisms established in the nuclear agreement. There is simply a demonstration of weakness in the IAEA when it comes to Iran. The sense is that Iran allows what it wants, and does not allow what it does not want.”

Netanyahu and Defense Minister Avigdor Lieberman are at odds with the Israeli defense establishment over whether to urge the U.S. to scrap the nuclear agreement with Iran, according to senior government and defense officials who asked to remain anonymous.

Netanyahu and Lieberman believe a U.S. withdrawal from the accord would be in Israel’s interest, but defense chiefs have reservations. Trump, who has called the accord "the worst deal ever negotiated," is due to recertify the nuclear deal on October 15 and inform Congress whether Iran is complying with the terms of the agreement.

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